Making Algorithm Generic

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Making Algorithm Generic

• Dr. Ying Xie

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• void selectionSort(int arr, int n)
• for (int startP 0 startP lt n-2 startP)
• //1. find the smallest number in the
  sublist
• int subscriptForSmallest startP
• For (int jstartP jltn-1 j)
• if (arrj lt
  arrsubscriptForSmallest)
• subscriptForSmallest j
• //2. swap the smallest number and the
  first number of this sublist
• int temp arrstartP
• arrstarP arrsubscriptForSmallest
• arrsubscriptForSmallest temp
• How about If I want to sort a double array?

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Function Templates

• C function templates are those functions which
  can handle different data type without separate
  code for each of them.
• Example template version of selectionSort.
• template lttypename Tgt
• void selectionSort(T , int n)
• template lttypename Tgt
• void selectionSort(T arr, int n)
• for (int startP 0 startP lt n-2 startP)
• //1. find the smallest number in the
  sublist
• int subscriptForSmallest startP
• For (int jstartP jltn-1 j)
• if (arrj lt
  arrsubscriptForSmallest)
• subscriptForSmallest j
• //2. swap the smallest number and the
  first number of this sublist
• T temp arrstartP
• arrstarP arrsubscriptForSmallest

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double arr15 2.0, 5.0, 1.0, 10.0,
2.3 selectionSort(arr1, 5) int arr26
1,0,3,4,5,2 selectionSort(arr2, 6) Account
accs100 ifstream accInfo("accInfo.dat") larges
tAccIndex -1 while(accInfogtgtidgtgtpingtgtamount)
largestAccIndex Account
acc(id, pin, amount) accountslargestAccI
ndex acc selectionSort(accs,
largestAccIndex1) ?
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• Operator Overload
• - Operator Overload With Friend Functions
• - Operator Overload with Member Functions

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Operator Overload With Friend Functions The
syntax to overload a binary operator for a class
with a friend function. Class myClass
public friend returnType
operator op (const myClass left, const myClass
right) private int mem1
double mem2 //implementing the operator op
as a friend function returnType operator op(const
myClass left, const myClass right)
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• Operator Overload lt with Friend Function
• class Account
• public
• Account()
• Account(string initID, string initPIN,
  double initBalance)
• void Deposit(double amount)
• bool Withdraw(double amount)
• double GetBalance()
• string GetID()
• string GetPIN()
• friend bool operator lt (const Account
  left, const Account right)
• private
• double balance
• string id
• string pin
• //implementing the operator lt as a friend
  function

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Operator Overload with Member Functions The
syntax to overload a binary operator for a class
with a member function. Class myClass
public returnType operator op
(const myClass mc) private int
mem1 double mem2 //implementing the
operator op as a friend function returnType
myClassoperator op(const myClass mc)
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• Operator Overload lt with Member Function
• class Account
• public
• Account()
• Account(string initID, string initPIN,
  double initBalance)
• void Deposit(double amount)
• bool Withdraw(double amount)
• double GetBalance()
• string GetID()
• string GetPIN()
• bool operatorlt (const Account)
• private
• double balance
• string id
• string pin
• //implementing the operator lt as a friend
  function

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How to make decisions overload with friend
function or overload with member function
acc1 lt acc2 ? view 1 operatorlt (acc1, acc2)
then implement it as a friend
function view 2 acc1.operatorlt(acc2)
then implement it as a member function
How about cout ltlt acc1? The only view is
operatorltlt(cout, acc1) then
you can only load ltlt as a friend function.
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• Operator Overload ltlt with Friend Function
• class Account
• public
• Account()
• Account(string initID, string initPIN,
  double initBalance)
• void Deposit(double amount)
• bool Withdraw(double amount)
• double GetBalance()
• string GetID()
• string GetPIN()
• friend ostream operator ltlt (ostream
  ostr, const Account acc)
• private
• double balance
• string id
• string pin
• //implementing the operator lt as a friend
  function